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I have surprisingly made the experience that you don't get back your reputation points if the bounty ends and no one has answered your question.
Even if you find an answer yourself before the bounty ends, and mark it as answer you're not getting your reputation points back.
Why is this so? Is it a bug or is it done intentionally? In my opinion, it would be good to redeem the credits to someone if he/she comes up with an answer finally.